Nippon Telegraph and Telephone Corp. said on Friday its group net profit dropped 10.3 percent to ¥290.33 billion in the first half of the fiscal year through September, compared to the same period a year earlier, dragged down by the slack mobile phone business.

NTT, which oversees its mobile phone unit NTT Docomo Inc. and other telecom group companies, posted group sales of ¥5.37 trillion, up 2 percent.

NTT Docomo was hit by lower revenue from its voice communication services amid tough competition with SoftBank Corp. and KDDI Corp.

For the full year to March, NTT cut its group net profit outlook to ¥529 billion from ¥586 billion and slashed sales forecast to ¥11.01 trillion from ¥11.20 trillion.